In addition to rechargeable battery cells, a rechargeable battery pack, such as that used with portable and mobile devices, typically contains circuitry that a battery charger interacts with while charging the rechargeable battery. For example, it is common for a rechargeable battery pack to include a thermal sensing component, such as a thermistor, so that the charger can monitor battery temperature. It is also conventional to include a memory device in the rechargeable battery pack. The memory device can be used to store battery identification and other information, allowing the charger to use appropriate voltage and charge current level. Typically each circuit element that the charger interacts with in a rechargeable battery has a dedicated contact to allow the charger circuitry to access or interact with the circuit element. Of course, the charger requires a mating contact for each battery contact in order to access the corresponding circuit in the rechargeable battery. Each contact on both the battery and charger adds to the direct material cost of the system, and adds to the likelihood of a defect occurring, adding to the cost of manufacturing. Reducing the number of contacts would therefore tend to decrease the cost to manufacture both the charger and the rechargeable battery.
Accordingly, there is a need for charging a rechargeable battery pack with a multiplexed contact.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.